70 hp 76 rude surges at wot

[gustafsonerik]

Hey everyone 76 70 hp rude runs great but at wot it starts to surge, I can get the boat up to 25mph but as soon as you hit wot it starts to surge,pull back 1/8 on the throttle and its fine, if I hit the choke or primer nothing changes still does it any advice????

 

[Bill3434]

Re: 70 hp 76 rude surges at wot

Have you check to see if the vent is open on your gas tank.

 

[fishfeatures]

Re: 70 hp 76 rude surges at wot

If Bill3434 suggestion doesn't solve it then squeeze the fuel bulb next time is happens and see if this sorts it , if so then check out the fuel pump.

 

[gustafsonerik]

Re: 70 hp 76 rude surges at wot

If Bill3434 suggestion doesn't solve it then squeeze the fuel bulb next time is happens and see if this sorts it , if so then check out the fuel pump.

Question my fuel line size to carbs is1/4 line is that to small should I upgrade them????

 

[Bill3434]

Re: 70 hp 76 rude surges at wot

Question my fuel line size to carbs is1/4 line is that to small should I upgrade them????

Did it ever run WOT with what you had now?

I'm not near my tanks but 1/4 does seem kind of small. I could be wrong on that.

 

[Watermann]

Re: 70 hp 76 rude surges at wot

Yeah, 1/4 inside hose diameter is correct, any bigger and they wouldn't seal up on the nipples causing fuel leaks under the cowl is not a good idea or an upgrade. Sounds like a fuel delivery problem, not enough fuel to sustain wot. Do you have a crapola attwood fuel line/primer bulb assembly or a OMC? It's easy to tell your attwood will be stiff and the OMC will be supple even after many many years of use. Check your fuel filter too, it may need replaced or cleaned out if it's just the screen in the pump.

 

[gustafsonerik]

Re: 70 hp 76 rude surges at wot

ok will do thanks one more quick question the vacuum line to the fuel pump 3/8 or 5/16

 

[JanKsterS]

Re: 70 hp 76 rude surges at wot

Prop is spinning, bushing went bad

 

[gustafsonerik]

Re: 70 hp 76 rude surges at wot

It's still surging would it make a difference if the air intake /air is off I took it off last summer now I'm wandering if putting it on would make a difference

 

[wrmdunker]

Re: 70 hp 76 rude surges at wot

I just fixed my 1974 70 hp Evinrude when two shops could not figure it out. Ran errattically and when acting up, I could not get to WOT and also started hard. Thought it might be spark. Here is what my rectifier lead looked like. Wire just rotted. Check that while you are at it as it seems to be age related. Fixed me.

 

[fireman57]

Re: 70 hp 76 rude surges at wot

Is this engine new to you or did it just start doing this? Get a buddy and run with your silencer off. have him drive and look into the carbs and make sure they are getting the same fuel rate. you will be able to see that easily. If they are then take your fingers/hand and close off the carbs one at a time and make sure that you feel them sucking air at the same rate. Trust me you will feel it. If this engine is new to you and everything is fine in what I told you then I will send you the service bulletin of what you need to do. It sounds scary but it was pretty easy to do. I have the same engine as you do and fought it for almost a year. did this and now it screams.

 

[gustafsonerik]

Re: 70 hp 76 rude surges at wot

thanks i will do sure send me the bulletin gustafsonerik@Hotmail.com thanks erik